1. Technical Field
Example embodiments of the present invention relate to methods for transmitting signal in a wireless communication system.
2. Related Art
In a wireless local area network (WLAN) system, a short training field (STF) is used for automatic gain control, packet estimation, initial time/frequency synchronization estimation, and so on. A transmitting terminal may generate multiple RP regions by allocating complex sequence elements to each subcarrier configured in frequency band for the STF. The transmitting terminal may generate a single orthogonal frequency division multiplexing (OFDM) symbol including a cyclic prefix (CP) and multiple RP regions. The transmitting terminal may generate multiple OFDM symbols through the above-described procedure.
If a single OFDM symbol in the STF is used for automatic gain control, a receiving terminal performs packet estimation and initial time/frequency synchronization by using RP regions included in other OFDM symbols of the STF. In this case, since the number of samples included in the RP region is small, there may be a problem of low signal to noise (SNR) ratio, and accordingly performance of the initial time/frequency synchronization may degrade.
Meanwhile, in a WLAN system, a long training file (LTF) may be used for fine time/frequency synchronization estimation, channel estimation, and so on. The LTF is configured with as the same number of OFDM symbols as those of the STF, and comprises a CP having twice length of the CP of the STF and two RP regions. Since the LTF includes more resources than resources needed for the fine time/frequency synchronization estimation and channel estimation, there is a problem of wasting resources.
On the other hand, a receiving terminal in the WLAN system has a problem that it cannot detect a collision of a frame being currently received by using a preamble of the received frame.